Mac Mail Sent emails disappear and re-appear

I have been having the same problem for several months: I hit "send" in Mac mail and the dialogue box would go away like normal and then nothing else would happen. No status bar on the bottom left or "whoosh" and then the sent mail does not appear in any of the sent mail folders (I have 3 email addresses and this happens on all 3). This does not happen 100% of the time but rather about 40%.

Since I can't tell if my email got sent, I then have to quit and re-start the program to try to make sure. SOmetimes it sends later out of nowhere (or the next day). SOmetimes it was sent but I can't really tell until I get a reply on it. Other times the sent emails magically re-appear out of nowhere in my sent mail box. Sometimes my inbox messages appear and disappear.

This is **** on wheels trying to work during the day when I can't ever tell if my emails have sent. And to top it off, when I hit the little "replied" arrow next to an inbox item, all I ever get is "Mail was unable to find your reply to the message “RE: credits”. You may have deleted the message."

Anybody seen anything like this? I have deleted my plist and mailboxes and re-created them several times to no avail. I have a godaddy account, a mobile me account and a gmail account. All 3 smae problem.

thanks